Spaniard Pedro de la Rosa was entrusted with the first laps of the new machine, complete with 2.4-litre V8 Mercedes engine, and his initial reaction was positive.

He said: “I am really pleased to have been at the wheel of the new car today. The car feels good initially, but it is of course too early to really understand its potential and we need to put a lot more laps on it.

“We have around 20 days of on-track running before the cars leave for Bahrain on Friday, March 3. As today is the initial shakedown, our focus will be to familiarise ourselves with the car and the Mercedes engine, and to run the various systems checks that are required with a new car.”

McLaren only just missed out on both world titles last season, beaten by Renault and Fernando Alonso despite a successful second half of the campaign.

Their chances were terminally damaged by a slow start to the season and chief executive Martin Whitmarsh has promised a steady stream of improvements to come before the season starts in Bahrain on March 12.

He said: “Everyone at McLaren-Mercedes is looking forward to the challenges ahead this season, and we took a major step in our preparations for 2006 today by starting to test the new car at Barcelona.

“The anticipation within the team as to how competitive the new car will be is great, particularly given the pace of our 2005 racer and the level of work that has been put into this project.

“However these are early days, we have a comprehensive programme to complete with the car over the next few weeks.

“This will mean hard and dedicated work from the whole team supported by our technology partners and official suppliers, including an aggressive schedule of upgrades to come on line before Bahrain.”